[DAG] Improve loads-from-store forwarding to handle TokenFactor

Forward store values to matching loads down through token
factors. Factored from D14834.

Reviewers: jyknight, hfinkel

Subscribers: hfinkel, nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D26080

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287773 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed